Mrs. Salmon is regarded as a key witness because she had seen Adams leave the Parker house wearing gloves and had seen him throw a hammer in the bushes.
The narrator of the story describes her as a person whose testimony would hold credibility in a courtroom. To the narrator, she appeared to be honest, caring and kind. The narrator further describes her as a person not having any malice.
Mrs Salmon had a slight accent but spoke clearly. She was not intimidated in the courtroom by the judge or the spectators. In the courtroom without hesitation she described the person she had seen outside Mrs. Parker's house. Her description of the person matched the appearance of the person standing in the dock; leaving no room for doubt that the person Mrs. Salmon had seen was the same as the person who was being charged for Mrs. Parker's murder.